Bathromelas hyaloscopa ( Meyrick & Lower, 1907 )

Beaver, Ethan P., 2023, Rediscovery and life history of Bathromelas hyaloscopa (Meyrick & Lower, 1907) Lepidoptera: Psychidae: Oiketicinae, Memoirs of the Queensland Museum | Nature 64, pp. 260-272 : 262-269

Bathromelas hyaloscopa ( Meyrick & Lower, 1907)

Buloke Bagworm Moth

( Figs 1-4 )

Holotype ♂: Victoria. N.W. from Casuarina suberosa / 4151 P. hyaloscopa TYPE.: M & L / 13 / SAMA 31- 000282 (in SAMA).

Additional material examined: In ANIC: 3♂ with cases, 2♀ with case, 1 larva, and 5 additional empty cases. ♂: Injune , Q., 3.10.1938, W.B. Barnard / ANIC 31-075892 . ♂ with case: 8.5 km SW Yetman, NSW, AUST. 28.94305°S, 150.70244°E. E.P. Beaver & M.F. Braby / Collected 4 Feb 2021 as larva on foliage of Allocasuarina luehmannii . Pupated Sep 2021, eclosed 16 Nov 2021. ♂ with case: Ellangowan NR, Leyburn, Qld, AUST. 430 m elev. 27.96260°S, 151.65175°E, E.P. Beaver & M.F. Braby / Collected 11-13 Feb 2021 as larva on foliage of Allocasuarina luehmannii . Pupated Sep 2021, eclosed 30 Oct 2021 / ANIC 31- 075884 . ♀ with case: Ellangowan NR, Leyburn, Qld, AUST. 430 m elev. 27.96260°S, 151.65175°E, E.P. Beaver & M.F. Braby / Collected 11-13 Feb 2021 as larva on foliage of Allocasuarina luehmannii . Pupated mid Oct 2021, eclosed 21 November 2021. / Dissection ID EPB-154 / ANIC 31-075885 . Larva with case: Ellangowan NR, Leyburn, Qld, AUST. 430 m elev. 27.96260°S, 151.65175°E, E.P. Beaver & M.F. Braby / Collected 11-13 Feb 2021 as larva on foliage of Allocasuarina luehmannii . ‘Mature larva preserved 26 Dec 2021 ’ ANIC 31-075886 . 1 Empty case: Ellangowan NR, Leyburn, Qld, AUST. 430 m elev. 27.96260°S, 151.65175°E, E.P. Beaver & M.F. Braby / Collected 11-13 Feb 2021 as larva on foliage of Allocasuarina luehmannii . / Approx 50 Chalcididae parasitoids from female pupa, none exited bag. 14 Sep 2021 / ANIC 31-075887 . 1 Empty case: Dthinna Dthinnawan NP, 15 km NNW Yetman, NSW, AUST. 28.77036°S, 150.74561°E, 03 Feb 2021, E.P. Beaver & M.F. Braby / Empty case on trunk of Allocasuarina luehmannii / ANIC 31-075888 . 3 additional empty cases with data as for the above example, except for ANIC numbers 31-075889, 31-07590, 31-075891. 1♀ with case, 25.52592°S, 148.68404°E, AUSTRALIA, QLD, 37km NNE of Injune, E. P. Beaver & M.F. Braby leg / ex larva on foliage ( Allocasuarina luehmannii ), 24 Mar 2022, eclosed 4 Sep 2022 / NA0018964463 .

In QM: 2♂, 1♀ with case, 1 larva with case, 2 additional empty cases. ♂: Injune . 26.9.1938 W.B. Barnard / T250899 / B. hyaloscopa M & L / QM T250899 . 1 Empty case: Jan 1986, 5 miles Sth Condamine R ., Chinchilla. Grace Lithgow (both in QM) . ♂ with case: Ellangowan NR, Leyburn, Qld, AUST. 430 m elev. 27.96260°S, 151.65175°E, E.P. Beaver & M.F. Braby / Collected 11-13 Feb 2021 as larva on foliage of Allocasuarina luehmannii . Pupated Sep 2021, eclosed 08 Dec 2021 / Dissection ID EPB-155 ’. ♀ with case: Ellangowan NR, Leyburn, Qld, AUST. 430 m elev. 27.96260°S, 151.65175°E, E.P. Beaver & M.F. Braby / Collected 11-13 Feb 2021 as larva on foliage of Allocasuarina luehmannii . Pupated mid Oct 2021, eclosed 05 December 2021. / Dissection ID EPB-153. Larva with case: Ellangowan NR, Leyburn, Qld, AUST. 430 m elev. 27.96260°S, 151.65175°E, E.P. Beaver & M.F. Braby / Collected 11-13 Feb 2021 as larva on foliage of Allocasuarina luehmannii / mature larva preserved 30 Oct 2021. Empty case: Ellangowan NR, Leyburn, Qld, AUST. 430 m elev. 27.96260°S, 151.65175°E, 11-13 Feb 2021, E.P. Beaver & M.F. Braby / Empty case on trunk of Allocasuarina luehmannii . Empty case: 8.5 km SW Yetman , NSW, AUST. 28.94305°S, 150.70244°E, 04 Feb 2021, E.P. Beaver & M.F. Braby / Empty case on trunk of Allocasuarina luehmannii .

In SAMA: 1 Empty case: Wilson, 6.8.97, A. Cummings / Metura elongatua? [sic].

Photographed specimen: 1 empty case, 13 Sep 2021, Lawes, 40 km E of Toowoomba, Qld, AUST. 27.55434°S, 152.33959°E iNaturalist observation 94712038 .

Description of stages

Late instar larva ( Fig. 2 A-C, 4C-D)

Length 28-45 mm, width at head capsule 4.5-5 mm. Head hypognathous, mostly matte black with irregular and individually highly variable pale cream markings. Antennae white basally. Ecdysial line light cream. Thorax smooth, lustrous, heavily sclerotised prothoracic shield. Prothorax with rust-coloured spiracle. Pro-, meso- and metathorax with irregular and variable pale cream markings arranged loosely into three dorsal columns. Central column straight, positioned medially, lateral columns slanted at acute angle. Legs three segmented with single tarsal claw, profemora pale cream dorsally.Abdomen less heavily sclerotised, dorsal aspect matte black, leathery, ventrally dark brown. Segments 1-2 with five pale cream ovoid to trapezoidal spots latero-ventrally along medial line. Segment 8 with two light creamcoloured spots laterally, segment 10 with cream spot laterally. Segments 1-8 with rust-coloured spiracle laterally. Uniordinal lateral penellipse of crochets on four pairs of ventral prolegs and a single pair of anal prolegs.

Case ( Fig. 3 )

Anterior to posterior aperture: 59-100 mm, width 7-13 mm. Female length 75-100 mm, males 59-69 mm. All cases with between one to four stems from hostplant as case adornment, stems 3-5 mm wide by 6-95 mm long, anchored from median of case, to posterior aperture, usually extending freely beyond posterior aperture. Remainder of bag with light grey silk covered in entirety with minute fragments of bark from hostplant, tightly packed together obscuring silk under-layer. Overall light khaki brown to light charcoal colour. Case is solid and structurally sound, similar to that of larger Lomera or Clania Walker, 1855 , and not flaccid or bag-like as in Hyalarcta Meyrick & Lower, 1907 or Metura Walker, 1855 .

Pupa

Male ( Fig. 2 D-F): Length 17 mm. Highly sclerotised, tan to matte black, wing-covers lustrous black. Frons with apical spine bifurcate to two nodes. Labial palps triangular. Maxilla inverse heart-shaped. Eyepiece semi-transparent. First pair of legs corrugated, others smooth. Dorsal abdomen with tergites II and III with both anterior and posterior row of spines, tergites I and IV-VII with only anterior row present.

Female ( Fig. 2 G-I): Length 40 mm. Elongate, simple, highly sclerotised, dark rust-red, darker dorsally, thoracic plates and head less heavily sclerotised. Tergites with reduced rows of spines, TVII with prominent semi-circular dorsal ridge.

Adult

Male ( Fig. 1 , 2 M-Q, 2T, 4E-F). Wingspan 26-30 mm. FW length 12-13 mm. HW length 7-8 mm.

Head. Rounded, eyes smaller than head capsule, wide-set, eye index ratio 1.6. Labial palps with single palpomere, narrow, triangular. Scales over frons and vertex range from light cream-grey through to black. Scape and pedicel subequal, flattened ovoid. Antennae black, bipectinate, apical flagellomere filiform. Rami 4-5x length of flagellum width in middle, heavily ciliated. Dorsal flagellum covered with pale cream scales.

Thorax dorsally and ventrally clothed with dark grey to charcoal scales, some specimens with cream scales over patagium and anterior tegula. Thoracic scutes deep rust-red to black beneath scales.

Legs ( Fig. 2T ). Short, clothed with dark brown to charcoal-black scales. Epiphysis elongate, very narrow, 2/3 the length of tibia. Single tibial spur distally on mid and hind legs. Aerolium reduced, ovoid. Two tarsal claws, curved.

Wings. Forewing elongate, narrow, triangular with blunt apex. Costa straight to very subtly concave at middle of discal cell. Margin convex, termen straight. Dense layer of charcoal to black scales, from piliform to short flattened along costa, basal area, basal 2/3rds of termen, wing fringe, elsewhere hyaline. Newly eclosed specimens ( Fig. 1 J-K, 4E-F) with complete layer of deciduous scales over wing surface, shed after eclosion. Veins light brown. R3+R4 stalked, Three M veins, M2+M3 stalked, two M veins in closed discal cell, free distally. CuP merged with A1 but not forming cell in basal area.

Hindwing. Costa convex, margin slightly sinuate, termen blunt at apex, straight at inner margin. Dense layer of charcoal to black scales along costa, inner basal area and along termen, wing fringe, elsewhere hyaline. Scale type in termen piliform. Deciduous scales over wing surface, shed after eclosion. Veins light brown, Sc and R 1 merged medially, three M veins present, M 2 +M 3 sometimes arising from same point on discal cell, discal cell with two M veins merged medially. CuP atrophied, three A veins present [Note: HT with aberrant venation left hindwing Sc and R free, M 1 not reaching margin, with discal cell open, M

2 forked].

Pregenitalia abdomen. Clothed with dark grey to charcoal/black scales, intersegmental membrane transparent. Sternites and tergites ( Fig. 2Q ) deep rust-red to dark brown. Tergite II rectangular, TIII- TVI trapezoidal with posterior margin becoming concave, TVII and TVIII with anterior margins slightly convex and posterior margin deeply concave, essentially bifurcate. All tergites with anterior lateral corners fine, elongate, becoming gradually longer on TIV-TVIII. Sternites II to SVII all roughly square with convex posterior margin in SIII-SVI and SVIII, anterior lateral corners narrow, elongate, increasing in length proportionally as general sternite size decreases, SVIII with anterior lateral corners modified to paired anterior apophyses, with apexes truncate, lateral sides of sternite slightly concave.

Male genitalia ( Fig. 2 M-P).Saccus weakly sclerotised, sub-triangular, posterior finger-like, elongate. Vinculum narrow, more heavily sclerotised medially and towards tegumen, lateral edges medially convex. Tegumen positioned at approximate middle of genitalia, broadest at outer margin, fused with uncus. Uncus broadly triangular, postero-lateral corners acute, posterior apex bifurcate, concave when viewed laterally, setose on dorsal aspect, membranous area present medially below apical bifurcation. ‘Transitellar arms’ sclerotised, short, linear. Valvae elongate, apexes bifurcate to two lobes, ventral lobe hooked, short spines at apex, with node on lateral edge, inner dorsal margin setose, dorsal lobe triangular with blunt apex, setose. Sacculus narrow, sinuate. Aedeagus elongate, approximately straight, ductus ejaculatorius and vesica smooth, pronounced asymmetrical ovoid at apex.

Female ( Fig. 2 J-L, 2R-S). Length 35-40 mm, elongate and narrow.

Head. Weakly sclerotised, hypognathous, bulbous, with rounded patch of sclerotisation at frons and above eye, eye present, tentorial pits present, antennae simple, single filiform antennomere, scape and pedicel appressed ovoid. Thorax. Dorsally highly sclerotised, dark brown, laterally and ventrally membranous, transparent. Wingless. Mesoscutum modified with pronounced thoracic hump above head and patagium. Lateral spine-like process present on thorax. Legs present, highly atrophied, weakly sclerotised dorsally and ventrally, two segmented with single apical hook on final segment. Pregenitalia abdomen membranous, transparent, in life with cream-yellow colouration of underlying tissue and eggs. Corethrogyne extensive, dense layer of iridescent golden scales covering TVII and SVII, with ring of scales around SVI and TVI, and the remaining sternites V to SIII all with medial patch of scales.

Female genitalia ( Fig. 2R ). Apophyses anteriores reduced, simple, weakly sclerotised arising from sclerotised sternite, SVII setose. Apophyses posteriores moderately long, segment VIII sclerotised. Antrum subtriangular, smooth. Corpus bursae rounded [damaged in dissection], diverticulum narrow. Ductus bursae short, narrow. Ovipositor short, simple.

Diagnosis

The main diagnostic morphological features compared with other Australian Psychidae are seven characters in the male, (mainly of wing vein morphology, and aspects of male genitalia and tergites) and additionally four characteristics of female adult and pupal morphology. In the male the forewing R5 is stalked from a point at discal cell with R3 + R4, hindwing with two M veins, three A veins, legs with basal tarsomere half-length of total tarsus, abdomen tergites TVII and TVIII have the posterior margin bifurcate with deep medial invagination, uncus apex bifurcate and with distinct central membranous area. Female with bulbous head, thoracic hump present, corethrogyne scales extensive and distributed beyond SVII, pupa with prominent dorsal ridge on TVII. The larval case is also distinctive by way of the tight-packed bark fragments with 1-4 twigs attached parallel from middle to close to posterior aperture.

LIFE HISTORY INFORMATION

Hostplant

The larval hostplant is the foliage of the Buloke Allocasuarina luehmannii (Casuarinaceae) , a dry woodland tree to 15 m widespread in eastern Australia. All specimens were collected from within the known range of this tree except for the South Australian larval case specimen. However, two other Allocasuarina are widespread in this region of South Australia – A. verticillata and A. muelleriana , both of which may form small trees. In captivity, larval specimens accepted Casuarina glauca , also Casuarinaceae ; however, larvae would not accept foliage from any other plant family offered, such as Fabaceae , Myrtaceae , Rosaceae , or Santalaceae . This species is expected to be a Casuarinaceae specialist, and the common name ‘buloke bagworm’ is suggested to reflect this. Host specificity to this degree is unusual in the Oiketicinae , which are typically broadly polyphagous.

Habitat and ecology

The habitat at the collection sites near Leyburn, Qld, Dthinna Dthinnawan NP, and near Yetman, NSW is largely similar; a dense dry Allocasuarina luehmannii and Callitris woodland with occasional Eucalyptus and Corymbia trees scattered throughout ( Fig. 4 A-B), receiving 350-600 mm of rainfall annually. The most abundant trees in these regions were A. luehmannii and Callitris , and larvae or empty cases were only located on A. luehmannii . A similar environment exists at Injune, Qld; however, the environments in western Victoria and in the Flinders Ranges are structurally different, and specific collection localities or habitats are unrecorded for this species within this south-western aspect of their known range.

Larvae were observed on both saplings and mature trees, generally on outer foliage around 1.3-2 m height. Larvae rest in dense foliage when inactive, and when feeding they travel along a casuarina needle to the distal apex, then feed backwards from this section. Larval duration is a minimum of two years. Larvae were late instars when collected in February or March, and pupation did not occur until September of the collection year, where only minor increase in overall length was observed over this duration. Pupae were always affixed to the main trunk or lower branches, or wedged in crevasses within the bark ( Fig. 4G ). Adult flight time and female eclosion is September through to early December. Males emerge in the mid afternoon at 15:45 hr, and attempt to fly immediately in captivity, suggesting that the species is diurnal. This may explain why no specimens are confirmed as to have been taken to light at night. As with other clear winged Oiketicinae where known, the adult males eclose with a complete set of deciduous scales across the entire wing surface area. These scales are shed as the insect vibrates the body and wings to heat itself before flight. One specimen ( Figs 1 J-L, 4E-F) was preserved before this heating process or flight could take place, in order to illustrate this feature, though some scale loss is apparent between eclosion and preservation. The basal areas of the wings are more heavily scaled with more strongly anchored scales. The eclosion of adult females was determined by the sudden appearance of a tuft of cast golden-coloured corethrogyne scales lodged in the posterior aperture of the larval case. When this was detected, the case was carefully slit open, and the female removed and preserved. Under natural conditions, the adult female will remain partially within her pupal exuvia with only the head and thorax exposed, positioned ‘head down’ at the posterior aperture of the case.

The posterior aperture is opened by use of her reduced but articulated legs, which also are used to push the corethrogyne scales out of the case. The females are not adapted for survival outside of the case. This behaviour is standard for oiketicine psychids where females are known. Egg laying was not observed but it is suspected to take place within the empty pupal shell of the female, as old empty pupae are often found filled with corethrogyne scales and eggshell fragments freely within this matrix. Empty cases appear to remain within the environment for a substantial period of time, possibly several years before breaking down or falling from the host tree. Some empty cases were found with infauna such as Arachnida: Clubionidae , Sparassidae , Insecta: various Blattodea, Coleoptera, Grylloidea , etc which utilised the cases for shelter and in some examples as food.

Parasitoids

Approximately 50 Brachymeria Westwood, 1829 , Chalcididae (det. E.P. Fagan-Jeffries) were reared from one case all from a single female pupa. The adult wasps were unable to exit the case for unknown reasons, and the majority were deceased upon opening the bag on the 14th of September 2021. One additional case was located with two small circular holes approximating the diameter of these same Brachymeria .

Distribution

Bathromelas is known to occur in scattered localities across the dry wooded areas of eastern Australia ( Fig. 5 ), in south-eastern Queensland from Injune, Leyburn, 8 km south of Chinchilla, 40 km east of Toowoomba , Bendidee SF ( Fig. 4G ), from northern New South Wales at 8 km SW of Yetman, the nearby Dthinna Dthinnawan NP, as well the single holotype specimen from ‘north-west Victoria’ , and a larval case from Wilson , near Kanyaka , South Australia. All of these localities are situated on or west of the Great Dividing Range. Some 1,100 km separates the Victorian specimen from those in NSW. However, this species is expected to be more widespread in inland eastern Australia in scattered localities where landscape-level areas of undisturbed old-growth stands of the hostplants still persist.

Figures

Figure 1. Adult male Bathromelas hyaloscopa (Meyrick & Lower, 1907) dorsal view, ventral, and data labels, A-C, holotype, D-F, specimen in QM from Injune, Qld., photos © Geoff Thompson, G-H, reared specimen in ANIC, J-L, reared specimen in EPBC. Scale bar 10 mm.

Figure 2. Bathromelas hyaloscopa A-C, larva, D-F, male pupa, G-I, female pupa, J-L, female, M-P, male genitalia EPB-155, Q, male abdomen tergites and sternites, R, female genitalia EPB-154, S, female head and thorax, cleared, T, male legs. Scale bars A-L 10 mm, M-P, R-T 1 mm, Q 2 mm.. Abbreviations are as follows: aa – apophyses anteriores, ap – apophyses posteriores, dr – dorsal ridge, ey – eye, fe – femur, lg – leg, ma – membranous area of uncus, SII-SVIII – sternite two to sternite eight, ta – tarsus, tg – tegumen, th – thoracic hump, ti – tibia, TI-TVIII – tergite one to tergite eight, un – uncus, va – valva, vi – vinculum.

Figure 3. Larval cases of Bathromelas hyaloscopa.

Figure 4. Habitat and live habitus of B. hyaloscopa. Habitat at A, Leyburn, Qld, B, Bendidee SF, Qld, C-D, live larva, E, newly eclosed male expanding wings and F, at rest, G, empty pupal cases on host tree at Bendidee SF.

Figure 5. Distribution map of B. hyaloscopa with published records as white circles (as approximate from Meyrick & Lower, 1907 and Turner, 1947) and cross-hatched circles for new records referred to in this text.